There are many granular comestible products, such as instant beverage mixes, sugar, salt, flour, and the like which are sold for commercial, institutional, and residential use. These products are often packaged in sealed containers which preserve the freshness and flavor of the product by excluding ambient air. However, once the package is opened, the oxygen and moisture in the air causes the quality of the product to deteriorate rapidly. Most packages are resealable to limit this deterioration. Unfortunately, the nature of the use of these products requires that they be dispensed reiteratively in small amounts, thus necessitating frequent opening of the container and re-exposure to the ambient air.
To overcome this problem, there have been developed in the prior art a large variety of dispensers for granular comestible products. These devices generally include an inverted container which feeds a subjacent dispensing chamber by gravital flow. In some of these devices, a lever or similar rotatable member is actuable to cause discharge of the granular material from the chamber. In other devices, the container must be inverted to fill the chamber, and then restored to its upright position; thereafter, inversion will cause discharge of the granular material in the chamber. In either case, the container design limits the amount of ambient air which contacts the granular material, and prolongs the freshness of the product.
One major drawback of the prior art devices is that the granular material absorbs sufficient moisture from the ambient air to become caked and form a coherent mass. Thereafter the gravitational flow effect does not occur, and the dispenser will not operate successfully. It is then necessary either to open the container and stir the contents, or to strike or otherwise vibrate the contents to fracture the coherent mass and restore the granular composition. The former course of action introduces even more ambient air into the container, while the latter invites damage or destruction of the container or dispenser.
Another drawback in some of the prior art devices is that the volume of granular material discharged in each dispensing operation is invariable. The quantity may be adjusted only by integral multiples of the discharge chamber volume. To overcome this deficiency, some devices have incorporated chambers which can be selectively varied in volume.
The following U.S. patents comprise the closest known prior art: U.S. Pat. Nos.:
2,530,730 PA1 3,866,805 PA1 3,836,055 PA1 2,507,557 PA1 3,308,995 PA1 3,414,172 PA1 4,159,791 PA1 3,211,334 PA1 3,258,174 PA1 2,535,845 PA1 2,515,735 PA1 3,716,173